Burzum - Hvis Lyset Tar Oss
Rather obscure, but quite simply the most beautiful, hypnotic, powerful, mythical, trance-like, pure, honest, real, scary, transcendent, insane, and serious-as-fuck album I've ever heard. REAL music that actually means something. The fact that it's Norwegian black metal made by a guy in prison for murder only adds to its reputation. Proved to me that music can be more than just music.
Metallica - Live Shit; Binge and Purge
Surely the greatest live album ever. 3 discs of awesome and flawless headbanging masterpieces performed by the greatest metal band of all time at the height of its power. 18 minute Seek and Destroy an undisputed highlight. Reminds me of the years between 18 and 22, the best years of any bloke's life.
Machine Head - Burn My Eyes
Coincided with me living in the UK for a year on a GAP year and having a ball. Effortlessly straddled numerous metal genres without falling into Nu-Metal bullshit. I honestly believe this album defined metal for the 90s. And the best news is they're now back to their best. One of the greatest album titles ever.
Oh and honourable mentions to Ulver, Dodheimsgard, Devin Townsend, Dream Into Dust, Blood Axis, Isis, Agalloch, and Godspeed You! Black Emperor.